This invention relates to a drill bit having slitting spurs spaced radially outwardly from a central point with convexly contoured portions therebetween which permit sharpening with a round file.
Helically fluted drill bits having a central point and spurs spaced radially outwardly therefrom are known. Such drill bits are illustrated in prior U.S. Pat. Nos. 421,293 to Loftie; 2,613,710 to Emmons; 3,824,026 to Gaskins; and French Pat. No. 944,587. However, none of the above appear to combine the features of a drill bit including a fluted, generally cylindrical body having a working end with a central work-engaging point, at least a pair of slitting spurs spaced radially outwardly therefrom, and a convexly contoured body portion interconnecting the point and a spur and intersecting a fluted region, with a spur having a sharpened slitting edge with an arcuate leading portion which first engages the work on rotation of the body. The intersection between the flute and the convexly contoured portion defines a sharp cutting edge. A drill bit according to the present invention provides the advantages of cleanly slitting the material to be bored and being able to be sharpened with a round file which is laid in and drawn across the convexly contoured portion interconnecting the central point and a spur.
A general object of the present invention is to provide a novel drill bit having the construction generally as set out above, and producing the stated advantages.
More specifically an object is to provide a novel drill bit having slitting spurs with arcuate leading edges able to cleanly engage and slit material at the periphery of a hole to produce a clean bore in the material.
A still further object of the present invention is to provide such a novel drill bit in which convexly contoured portions between the point and spur intersect the flutes in the body of the bit permitting sharpening with a round file.